In recent years there has been a demand for silver halide photosensitive materials, especially camera color sensitive materials, which have excellent sharpness and color reproduction properties at high photographic speed as typified by the materials which have a ISO speed of 100 or an ISO speed of 400 (Super HG-400) and which provide a high image quality.
DIR couplers are known as a means of improving sharpness and color reproduction properties; but more recently, other compounds, including those represented by general formula (R-I) of the present invention, have been proposed to improve these properties in JP-A-60-185950. (The term "JP-A" as used herein signifies an "unexamined published Japanese patent application".) More precisely, while sharpness and color reproduction have been improved by these compounds, their use resulted in changes in photographic properties as the developer became fatigued, and thus the conjoint use of these compounds and so-called DIR compounds was proposed in JP-A-61-255342. Furthermore, the use of the above mentioned compounds at the same time with DIR compounds has also been disclosed in more recent patents, for example in JP-A-1-107256, JP-A-1-259359, JP-A-1-269935 and JP-A-2-28637, but not only are the levels of color reproduction and sharpness achieved inadequate with the sensitive materials in which these are used, but when these materials are processed using the processing methods generally used in commercial laboratories at the present time, which is to say continuous processing with replenishment of the developer, the developer sometimes becomes more active and, conversely, it sometimes becomes less active and it has become clear that stable performance cannot be obtained.
On the other hand, hydrolysis type DIR compounds and couplers which improve sharpness and color reproduction without changing the activity of the developer as indicated above have also been proposed, for example, in JP-A-57-151944, JP-A-58-205150, JP-A-1-280755 and U.S. Pat. No. 4,782,012. More precisely, the fluctuation in developer activity has been improved by means of DIR couplers and DIR compounds which release leaving groups of the type such that the development inhibitors are hydrolyzed in the developer and the development inhibiting activity is essentially lost, but their effect in this respect has still been inadequate. In particular, in those instances where a development inhibitor is deactivated and an aryl oxide ion is released in the developer which is taken up into coupler oil droplets in the photosensitive material, there is clearly changed the coupling activity of the couplers and as a result a change in photographic performance also occurs.
Furthermore, timing type DIR couplers also give rise to problems with respect to the stability of the compounds and preparative costs, and those which are eliminated from the coupler via sulfur, such as those disclosed in U.S. Pat. No. 4,782,012 for example, have a low coupling activity, which is to say that the development inhibitor release rate is slow and so there is a problem in that an adequate improving effect on color reproduction and sharpness is not obtained.